With the new tax, pot sales in Arizona could bring the state as much as $40 million in yearly revenues, according to estimates.

Arizona became the 15th state to approve of medical marijuana last November. State residents should be able to buy medical marijuana with a doctor's prescription as early as this summer.

The added tax, announced today, is unlikely to discourage the types of entrepreneurs now attending "Marijuana University" at a Tuscon strip mall. According to a local magazine, the founder and head of the "school" is Allan Sobol, who tells his students: “This is a new billion-dollar industry coming to Arizona. Look at the horizon. There’s a giant tsunami headed straight this way."

And here's what's on a sign on the wall in Sobel's classroom, which is attracting students from other states who plan to take the lessons home to set up medical dispensaries.

100,000 potential patients

124 dispensaries

806 average patients per dispensary

5 ounces per patient, per month

$400 an ounce

$19,344,400.00 annual gross sales [per dispensary]

“One hundred twenty-four dispensaries is your best friend,” Sobol says, referring to the number of licenses the state is planning to approve. “If you happen to be lucky enough to get one of those licenses, you are a multimillionaire. Period. It’s almost a monopoly.”